Qualitative determination of inorganic anions in incendiary device residues by capillary electrophoresis

Abstract

The determination of the inorganic anions present in residues from improvised incendiary devices (IIDs) is of interest to the police to obtain information about the type of device employed, and to determine its composition. The Chemical Ignition Molotov Cocktail (CIMC) is an IID of increasing use. In this paper, an analytical procedure for sample treatment and qualitative analysis by CE is applied to determine the anionic composition of CIMC residues. First, a comparison of two CE methods for the separation of three target anions present in CIMCs (sulfate, chlorate, and chloride) was made by considering chromate- and pyromellitic acid (PMA)-based buffers. After the analysis of CIMC samples prepared in the laboratory under controlled conditions (Lab-CIMC samples) perchlorate was found to be a novel target anion useful for the identification of CIMCs. This result allowed recommendation of the PMA-based buffer to police forces for the separation of target anions in CIMC samples, even if chloride and sulfate may be partially overlapped under these conditions. Finally, the analytical procedure was applied to the analysis of real CIMC residues and soil samples. Chlorate and perchlorate are the target anions making possible the identification of CIMC since the other studied anions may have originated from other sources.